Medical Masks Versus N95 Respirators for Preventing COVID-19 Among Health Care Workers
Authors: Kevin Hedges, Marianne Levitsky, Genevieve Marchand, Lidia Morawska, Luc Bhérer, Marie-Claude Letellier
Journal: Annals of Internal Medicine (2023)

LettersJuly 2023Medical Masks Versus N95 Respirators for Preventing COVID-19 Among Health Care WorkersFREEKevin Hedges, MAppSc, PhD, CIH, COH, Marianne Levitsky, MES, CIH, ROH, Genevieve Marchand, PhD, Lidia Morawska, PhD, Luc Bhérer, MD, Marie-Claude Letellier, MD, MSc, McbAKevin Hedges, MAppSc, PhD, CIH, COHCanadian Aerosol Transmission Coalition, Ottawa, Ontario, CanadaSearch for more papers by this author, Marianne Levitsky, MES, CIH, ROHWorkplace Health Without Borders, Mississauga, Ontario, CanadaSearch for more papers by this author, Genevieve Marchand, PhDIRSST, Montreal, Quebec, CanadaSearch for more papers by this author, Lidia Morawska, PhDInternational Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Queensland, AustraliaSearch for more papers by this author, Luc Bhérer, MDCIUSSS de la Capitale-Nationale, Quebec City, Quebec, CanadaSearch for more papers by this author, Marie-Claude Letellier, MD, MSc, McbACISSS Gaspésie, Gaspé, Quebec, CanadaSearch for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/L23-0076 SectionsAboutVisual AbstractPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail TO THE EDITOR: Many professionals, including those who have expertise in aerosol science and respiratory protection, have expressed concern about the “ethical nature” of Loeb and colleagues' study (1). Many will state that there is, in fact, no equipoise.A letter (2) concerning the trial design as published at ClinicalTrials.gov was sent in April 2021 to the Canadian Government, Responsible Conduct of Research, Tri-council Federal Office, from occupational health and safety professionals located around the world. It noted the following:Our primary concern is that the methodology puts health care workers at risk of becoming infected with SARS-CoV-2.Secondly, it supports health care workers wearing surgical masks which do not provide effective personal protection against highly infectious aerosols, whereas properly fit tested filtering face-piece respirators, and continuous use as part of a comprehensive respiratory protection program, do.Thirdly, we have significant concerns about the questionable study design. The likelihood of flawed findings is high. Flawed findings are often used to justify inadequate safety protections for health care workers.Comments in the Annals of Internal Medicine are unfortunately limited to a maximum of 400 words. To elaborate on this comment, we make reference to a follow-up letter (3) sent to the Editor in Chief of Annals with the support of 33 professionals—along with extensive information and citations—to corroborate that there was no equipoise.We believe that Loeb and colleagues' study violated the principle of equipoise, which requires that a participant be enrolled in a trial only if there is true uncertainty about which of the trial groups is likely to benefit the participants (2–4). Without equipoise, a study is unethical. In this case, there was at the time of the study sufficient evidence, amplified since that time, to show that N95 respirators are superior to surgical masks for protection from inhalable aerosol transmissible diseases.We therefore challenge whether a randomized controlled trial was necessary (5) to prove whether filtering facepiece respirators provide more protection against inhalable infectious aerosols compared with a surgical mask. Sharing a conclusion of failure to show a doubling of hazard for medical masks compared with N95 respirators due to a poorly designed study will lead to misinterpretation and threaten the lives of health care workers around the world.References1. Loeb M, Bartholomew A, Hashmi M, et al. Medical masks versus N95 respirators for preventing COVID-19 among health care workers. A randomized trial. Ann Intern Med. 2022;175:1629-1638. [PMID: 36442064] doi:10.7326/M22-1966 LinkGoogle Scholar2. Hedges K, Farquhar A, Levitsky M, et al. Letter to the Government of Canada, Responsible Conduct of Research, Tri-council Federal Office Panel on the Responsible Conduct of Research, The Secretariat on Responsible Conduct of Research (SRCR). 19 April 2021. Accessed at https://healthcareworkersaustralia.com/wp-content/uploads/2020/08/REBTri_council_letterrevisedfinal19Apr2021final.pdf on 2 May 2023. Google Scholar3. Hedges K, Marchand G, Levitsky M, et al. Letter to Editor in Chief of Annals of Internal Medicine. 10 January 2023. Accessed at www.aerosoltransmissioncoalition.ca on 2 May 2023. Google Scholar4. Alexander JH. Equipoise in clinical trials: enough uncertainty in whose opinion. Circulation. 2022;145:943-945. [PMID: 35344405] doi:10.1161/CIRCULATIONAHA.121.057201 CrossrefMedlineGoogle Scholar5. Hedges K. Re: Adapt or die: how the pandemic made the shift from EBM to EBM+ more urgent. Online comment. BMJ Evid Based Med. 9 August 2022. Accessed at https://ebm.bmj.com/content/27/5/253.responses on 2 May 2023. Google Scholar Comments0 CommentsSign In to Submit A Comment Author, Article, and Disclosure InformationAuthors: Kevin Hedges, MAppSc, PhD, CIH, COH; Marianne Levitsky, MES, CIH, ROH; Genevieve Marchand, PhD; Lidia Morawska, PhD; Luc Bhérer, MD; Marie-Claude Letellier, MD, MSc, McbAAffiliations: Canadian Aerosol Transmission Coalition, Ottawa, Ontario, CanadaWorkplace Health Without Borders, Mississauga, Ontario, CanadaIRSST, Montreal, Quebec, CanadaInternational Laboratory for Air Quality and Health, Queensland University of Technology, Brisbane, Queensland, AustraliaCIUSSS de la Capitale-Nationale, Quebec City, Quebec, CanadaCISSS Gaspésie, Gaspé, Quebec, CanadaDisclosures: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=L23-0076. 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